AWS RDS MySQL Instance starts performing same SQL SELECT query much slower under certain loading

Question

I'm running performance testing on my application that lives in AWS environment and I see a weird behavior of the DB after certain loading.

When I have more than 1500 queries per second to the RDS MySQL, the queries are performed much slower.

The query is a SELECT statement from one table by 2 columns, we have an index created for these 2 columns.

The current setup is the following:

RDS MySQL r5.2xlarge InnoDB

Increasing the type of RDS instance doesn't help.

Is there any way to improve the performance of the current setup?

Is there any limitation on SELECT queries to the same Table or using the same Index?

Any suggestions would be much appreciated.

Answer 1

The problem was on the application level with ORM, so this question is not relevant anymore.